/**     vbuf.c - virtual buffering of type and symbol strings
 *
 *      The term virtual is somewhat misleading.  It does not mean that
 *      the string buffering is performed using virtual memory.
 */


#include "compact.h"



/**     VBufInit - initialize virtual buffer
 *
 *      VBufInit (buf, count)
 *
 *      Entry   buf = pointer to buffer header
 *              count = size of buffer
 *
 *      Exit    buffer initialized to zero
 *              buf->Blocksize = count
 *
 *      Returns nothing
 */


void VBufInit (VBuf *Buf, unsigned int count)
{
    memset (Buf, 0, sizeof (VBuf));
    Buf->BlockSize = count;
}




/**     VBufCpy - copy string to virtual buffer
 *
 *      pStr = VBufCpy (buf, src, count);
 *
 *      Entry   buf = pointer to buffer header
 *              src = pointer to source string
 *              count = number of bytes in string
 *
 *      Exit    string copied to buffer if space available
 *              new buffer allocated if necessary
 *              buffer header updated
 *
 *      Returns NULL if count > exceeds buffer max
 *              pointer to copied string
 */


uchar *VBufCpy (VBuf *Buf, uchar *Src, unsigned int Bytes)
{
    uchar  *Target = NULL;
    VBlock *NewBlock;

    if (Bytes <= Buf->BlockSize) {
        if (Bytes > Buf->FreeBytes) {
            NewBlock = (VBlock *)CAlloc (sizeof (VBlock));
            NewBlock->Address = (uchar *)Alloc (Buf->BlockSize);
            if (Buf->CurBlock) {
                // link to current block
                Buf->CurBlock->Next = NewBlock;
            }
            else {
                // first block
                Buf->Block = NewBlock;
            }
            Buf->NumBlocks++;
            Buf->CurBlock = NewBlock;
            Buf->NextByte = NewBlock->Address;
            Buf->FreeBytes = Buf->BlockSize;
        }
        Target = Buf->NextByte;
        memcpy(Target, Src, Bytes);
        Buf->NextByte += Bytes;
        Buf->FreeBytes -= Bytes;
        Buf->CurBlock->Size += Bytes;
    }
    return (Target);
}




/**     VBufRead - read type string to virtual buffer
 *
 *      pStr = VBufRead (buf, count, leaf);
 *
 *      Entry   buf = pointer to buffer header
 *              count = number of bytes in string
 *              leaf = leaf index
 *
 *      Exit    string copied to buffer if space available
 *              new buffer allocated if necessary
 *              buffer header updated
 *
 *      Returns NULL if count > exceeds buffer max
 *              pointer to copied string
 */


uchar *VBufRead (VBuf *Buf, unsigned int Bytes, ushort leaf)
{
    uchar  *Target = NULL;
    VBlock *NewBlock;

    if ((Bytes + sizeof (TYPTYPE)) <= Buf->BlockSize) {
        if (Bytes > Buf->FreeBytes) {
            NewBlock = (VBlock *)CAlloc (sizeof (VBlock));
            NewBlock->Address = (uchar *)Alloc (Buf->BlockSize);
            if (Buf->CurBlock) {
                // link to current block
                Buf->CurBlock->Next = NewBlock;
            }
            else {
                // first block
                Buf->Block = NewBlock;
            }
            Buf->NumBlocks++;
            Buf->CurBlock = NewBlock;
            Buf->NextByte = NewBlock->Address;
            Buf->FreeBytes = Buf->BlockSize;
        }
        Target = Buf->NextByte;
        ((TYPPTR)Target)->len = Bytes + sizeof (ushort);
        ((TYPPTR)Target)->leaf = leaf;
        read (exefile, &((TYPPTR)Target)->data[0], Bytes);
        Buf->NextByte += Bytes + sizeof (TYPTYPE);
        Buf->FreeBytes -= Bytes + sizeof (TYPTYPE);
        Buf->CurBlock->Size += Bytes + sizeof (TYPTYPE);
    }
    return (Target);
}




/**     VBufSet - initialize space in virtual buffer
 *
 *      pStr = VBufSet (buf, init, count);
 *
 *      Entry   buf = pointer to buffer header
 *              init = character to initialize buffer
 *              count = number of bytes in string
 *
 *      Exit    string initialized in buffer if space available
 *              new buffer allocated if necessary
 *              buffer header updated
 *
 *      Returns NULL if count > exceeds buffer max
 *              pointer to initialized string
 */


uchar *VBufSet (VBuf *Buf, uchar Chr, unsigned int Bytes)
{
    uchar  *Target = NULL;
    VBlock *NewBlock;

    if (Bytes <= Buf->BlockSize) {
        if (Bytes > Buf->FreeBytes) {
            NewBlock = (VBlock *)CAlloc (sizeof (VBlock));
            NewBlock->Address = (uchar *)Alloc (Buf->BlockSize);
            if (Buf->CurBlock) {
                // link to current block
                Buf->CurBlock->Next = NewBlock;
            }
            else {
                // first block
                Buf->Block = NewBlock;
            }
            Buf->NumBlocks++;
            Buf->CurBlock = NewBlock;
            Buf->NextByte = NewBlock->Address;
            Buf->FreeBytes = Buf->BlockSize;
        }
        Target = Buf->NextByte;
        memset (Target, Chr, Bytes);
        Buf->NextByte += Bytes;
        Buf->FreeBytes -= Bytes;
        Buf->CurBlock->Size += Bytes;
    }
    return (Target);
}



/**     VBufFirstBlock - return first block in virtual buffer
 *
 *      pBlock = VBufFirstBlock (buf)
 *
 *      Entry   buf = buffer header
 *
 *      Exit    none
 *
 *      Returns pointer to first block in buffer block list
 */


VBlock *VBufFirstBlock (VBuf *Buf)
{
    return (Buf->Block);
}




/**     VBufNextBlock - return first block in virtual buffer
 *
 *      pBlock = VBufNextBlock (pBlock)
 *
 *      Entry   pBlock = current block in list
 *
 *      Exit    none
 *
 *      Returns pointer to next block in buffer block list
 */


VBlock *VBufNextBlock (VBlock *Block)
{
    return (Block->Next);
}